The Genetic Effects of rs7903146 and Dietary Intake on Type 2 Diabetes Mellitus Risk in a Healthy Population

Type 2 diabetes mellitus (T2DM) is a global epidemic linked to 1.6 million deaths in 2016. Diet, lifestyle and environment contribute significantly to T2DM-risk. Genome-wide association studies identify the transcription factor 7-like 2 (TCF7L2) rs7903146 (C/T) gene as one of the most important associated with T2DM-risk. The T-allele is associated with a two-fold increase in relative risk of T2DM across different populations. However, most studies associating genetic effects of dietary intake on rs7903146 and T2DM-risk utilised volatile instantaneous measures of glucose(5) and focussed on individual macronutrients. Understanding the association of rs7903146 and overall macronutrient intake using a stable blood homeostasis marker may provide a fuller insight into T2DM-risk.

The study included data for all variables (participant characteristics: sex (female/male), age (years), height (cm), weight (kg), body mass index (BMI) (kg/m2), body fat percentage (%), fat mass (kg), lean mass (kg), waist/hip (ratio), dietary intake, HbA1c (mmol/mol and %) and physical activity (hours/week). All data was collected at St Mary's University between April to July 2019. Participants was genotyped and allocated into two groups: major allele (C) homozygote versus minor allele (T) homozygote plus heterozygote. T2DM-risk was assessed through their value of HbA1c and participants were classified as follows: normal (<42mmol/mol/ <6.0%), pre-diabetic (42 to 47 mmol/mol/ 6.0% to 6.4%), diabetes (48mmol/mol /6.5% or over).

Inclusion criteria

Eligibility criteria required healthy adults free from metabolic condition and free from medication affecting glycated haemoglobin levels.

Exclusion criteria

Individuals with HbA1c levels ≥48 mmol/mol or ≥6.5% were excluded due to a classification as T2DM (WHO, 2011).